I’ve removed plenty of DCs and Domains in my years. In fact I recently blogged about how remove a failed DC here. It seems sometimes after removing a domain from your environment doesn’t remove it entirely.
You may see a message that says the following:
The trusts between this domain (abc.local) and the following domain(s) are in an error state:
xyz.abc.local (inbound), the error is:
The specified domain either does not exist or could not be contacted. (0x54B)
Normally this message is pretty self explanatory. However if you removed the domain and it still shows up then it can cause some unrest.
To remove those messages and to completely remove those messages you will want to open ADSIEdit.msc from a DC and expand out the Domain partition. From there select CN=System. Now you should see in the results pane a listing of objects. In there you should find the domain in question as a trustedDomain class. If indeed the domain has been removed go ahead and right click it and delete it.